Product Information: The air pressure switch enacts safety checks that ensure the fan is in full working order. It ensures that, if the fan fails within the boiler, there would not be a build up of noxious gases with no means of venting them. The PCB closely monitors the air pressure switch to make sure it is fully operational before the unit is fired up, preventing the appliance from starting without one of its key safety mechanisms.
This part is present in 3 different boilers in the Worcester range including the Worcester 24SI II NG , 28SI II NG , RD628 FSN NG BRITISH GAS .